Hot-gas reciprocating machine



Aug. 17, 1965 A. A. DROS 3,200,582

HOT-GAS RECIPRQCATING MACHINE Filed Nov. 4, 1963 e Sheets-Sheet 1 Ii///a no 17A FIG.1

INVENTOR ALBERT A. DROS GEN Aug. 17, 1965 A. A. DRos HOT-GASRECIPROCATING MACHINE Filed Nov. 4, 1963 6 Sheets-Sheet 2 F r 8 5 I1 m 9a in NM I 3 9 mm mq v9 om am .2

INVENTOR.

ALBERT A. DROS AGENT Aug. 17, 1965 A. A. DROS 3,200,582

HOT-GAS RECIPROCATING MACHINE Filed Nov. 4, 1963 6 Sheets-Sheet 3 FIG.3

INVENTOR.

ALBERT A. DROS BY MA- AGEN Aug. 17, 1965 6 Sheets-Sheet 4 Filed Nov. 4,1963 'IFZI INVENTOR.

ALBERT A. DROS AGENT Aug. 17, 1965 A. A. DRos 3,200 58 HOT-GASRECIPROCATING MACHINE Filed Nov. 4, 1963 6 Sheets-Sheet 6 INVENTOR.

ALBE RT A, DROS BY JZM/ AGENT United States Patent The invention relatesto a hot-gas reciprocating machine, particularly a cold-gasrefrigerator, comprising one or more compression spaces of variablevolume, cornmunicating with one or more expansion spaces also ofvariable volume, said spaces having, in operation of the machine,different mean temperatures, whilst the connection between the spacesincludes regenerators, through which a medium can flow to and frobetween the sai spaces, whilst the machine comprises piston-like bodiesadapted to move with a phase difference for varying the volumes of theexpansion space and of the compression space, said piston-like bodiesbeing coupled with a driving gear.

In the scope of the present invention the term hot-gas reciprocatingmachine is to denote not only a hot-gas engine but also a cold-gasrefrigerator and a heat pump operating on the reverse hot-gas engineprinciple. For the sake of simplicity the unit in which thethermodynamic cycle is performed is termed hereinafter the cooling unit.

In known machines of the kind set forth the piston-like bodies varyingthe volumes of the compression space and of the expansion space areconnected via piston rods, connecting rods, yokes, toothed wheels andthe like with the driving gear. The'construction of the driving gearwith these machines is further complicated by the requirement that for asatisfactory operation of said machine the movements of the piston-likebodies should have a phase difference of about 90. Hitherto this broughtabout complicated structures with many points of rotation subjected towear, all of these structures comprising a great number of the aforesaidcomponent parts.

In order to mitigate these disadvantages it has been proposed toestablish the coupling between the driving gear and the piston-likebodies by means of fluid columns.

movable in ducts, so that power can be transferred by said fluid columnsfrom the driving gear to the relevant pistonlike bodies and/orconversely. The term coupling is to be understood in this connection tomean not only a fixed connection between the pistons and the drivinggear but also a member which controls the movement of the pistons inaccordance with the movement of the driving gear or conversely. In thisway a simple coupling between the driving gear and the relevant pistonsis obtained.

The invention has for its object to provide a further improvement of ahot-gas reciprocating machine with the coupling described above betweenthe pistons and the driving gear and is characterized in that themachine comprises at least two pump units, each of which comprises apair of double-acting pistons adapted to reciprocate in closed,fluid-filled cylinders and in that the machine comprises furthermore atleast two pairs of cooling units, each comprising a compression piston,adapted to reciprocate in a cylinder, a cooler,;a regenerator, a freezeror heater and an expansion piston adapted to reciprocate in a cylinder,whilst each of the spaces of one pair of cooling units positioned, onthe side remote from the Working space of the expansion pistonsassociated with said space, communicates with one of the spaces oneither side of one of the pistons of the first pump unit and each of thespaces positioned, on the side remote from the working space of thecompression piston associated with said space, communicates with one ofthe spaces on either side of one of the pistons of the second pump unit,whilst each of the spaces of the other pair of cooling units positioned,on the side remote from the working space of the expansion pistonassociated with said space, communicates with one of the spaces oneither side of the other piston of the second pump unit and each of thespaces positioned on the side remote from the working space of thecompression piston associated with said space, communicates with one ofthe spaces on either side of the other piston of the first pump unit.

An advantage of said machine consists in that with each pump unit thespaces on either side of one of the doubleacting pistons communicatewith the spaces on the side of the compression pistons of a pair ofcooling units remote from the working space, whereas the spaces oneither side of the other double-acting piston of said pump unitcommunicate with the spaces on the side remote from the working space,of the expansion pistons of the other pair of cooling units. It is thusensured that the variation of forces on the pump rod, during themovement of the rod in one direction, is substantially identical to thevariation of forces on the pump rod during the movement of said rod inthe other direction. As a result the load on the driving gear is asuniform as possible. A further advantage of said arrangement is that theenergy released during the expansion of the working medium in one pairof cooling units via the fluid columns and one double-acting piston of apump unit, is directly transferred to the other double-acting piston ofsaid pump unit, said energy being again transferred via the fluidcolumns to the compression pistons. The eiliciency of the machine isthus extremely furthered.

Although the pump units and the pairs of cooling units may be arrangedrelatively to each other in an arbitrary manner, an advantageous andcompact construction of a hot-gas reciprocating machine is obtained byan arrangement of the units in accordance with the invention, which ischaracterized in that the pump units are pairwise arranged in a V andare connected with a common crank shaft, whereas each of the coolingunits is arranged substantially between planes intersecting in thecentre line of the crank shaft and determined by the centre lines of thepump units, and in that in a projection to a plane at right angles tothe centre line of the crank shaft the centre lines of the two pumpunits and the centre line of each cooling unit form a triangle.

An advantageous embodiment of the hot-gas reciprocating machinedescribed above is characterized in accordance with the invention, inthat one pair of cooling units is arranged between the two pump units sothat the spaces on the side remote from the working space of thecompression pistons associated with said cooling units are orientatedtowards the first pump unit communicating with said space, whilst thespaces, on the side of the expansion pistons of said cooling unitsremote from the working space, are orientated towards the second pumpunit associated with said space, whereas the other pair of cooling unitsis arranged between the two pump units so that the spaces on the side ofthe compression pistons associated with said cooling units remote fromthe working space are orientated towards the second pump unitcommunicating with said space and the spaces on the side of theexpansion pistons associated with said cooling units remote from theworking space are orientated towards the first pump unit communicatingwith said space. Thus a compact structure of a hot-gas reciprocatingmachine is obtained, which occupies little space and in which onlycomparatively small quantities of fluid are required due to the shortlines of connection between the fluid-filled spaces in the pumpmunicating with said pump units is disposed in a plane extendingparallel to and in front of theplane of the pump units, whereas theother pair of cooling units associated with said pump units is disposedin a plane extending parallel to and behind the plane of the pump 7units and the cooling units are arranged in their respective planes sothat,'in a projection to the plane of the pump units, the centre linesof the cooling units of one pair intersect the centre lines of thecooling units of the other pair.

A further advantageous hot-gas reciprocating machine embodying theinvention has the feature that in each cooling unit each piston isconnected with a control-slide, which is displaced'during the movementof the piston associated with it along a wall portion of thefluid-filled spaces on the side remote from the working space in saidspace, whilst in the wall portion controlled by said slide at least onefluid inlet and one fluid outlet are provided, said openings beingarranged so that the fluid inlet duct is released, when the piston movesbeyond its extreme, prescribed position, whereas the fluid outlet ductis released, when the piston occupies its deepest position in thecooling unit.

By using the control-slide according to the invention structurallysimple means ensure that the extreme posi- 'tions of the pistons arealways the same. This has the advantage that the pistons cannot comeinto contact with the cylinder boundaries, which might give rise tobreakage, whilst, in addition, since the extreme positions are fixed,the volume variations of the working spaces are the same, so that alsothe pressure variation in said spaces does not change.

An advantageous hot-gas reciprocating machine embodying the invention ischaracterized in that the cylinder of each cooling unit, in which apiston is adapted to move, terminates in a further cylindrical part, inwhich the piston-like control-slide is adapted to move, whilst themachine comprises one or more ducts establishing a communication betweenthe spaces on either side of the control-slide, whilst the fluid inletduct and the fluidoutlet duct join the wall of the further cylindricalpart.

In order to start the hot-gas reciprocating machine according to theinvention the pistons must occupy given positions in the cooling units,which positions correspend with the pistons of the pistons of the pumpunits at the instant concerned. In order to move the pistonlike bodiesinto the correct positions, the hot-gas reciprocating machine accordingto the invention has the feature that each of the fluid-filled spaces ineach cooling unit communicates with a further fluid-supply duct, thepassage of which is blocked during the operation of the machine, whereasat the position of the control-slide the opens out a furtherfluid-outlet duct, the passage of which can be released when the machineis prepared for a start, whilst the openings of the fluid-outlet ductsare disposed so that they are free when the relevant piston occupies itsstarting position.

In order to move the pump pistons into their starting positions whichcorrespond, as a matter of course, with the aforesaid starting positionsof the pistons of the cooling units, the hot-gas reciprocating machineaccording to the invention is characterized in that the interconnectedpistons of each of the pump units are furthermore connected with afurther piston-like body located in line with their centre line, saidbody being adapted to reciprocate in a closed cylinder, whilst in thespace above said piston-like body there opens a fluid-inlet duct, bywhich compressed fluid can be inserted into said space,

so that the pistons of the pump units occupytheir starting positions.

A further advantageous hot-gas reciprocating machine embodying theinvention is characterized in that the machine comprises a pumpdevice,.the pump duct of which can be caused to communicate by way of acontrolmember with the various fluid-supply ducts of the machine, whilstthere is furthermore provided a fluid con tainer, with which cancommunicate fluid-outlet ducts of the machine via a control-member. r n

The invention will be described more fully with reference to thedrawing, which is given by way of example.

FIGS. 1, 2 and 3 show partly in a sectional view and in three orthognalelevations a hot-gas reciprocating machine formed by a cold gasrefrigerator. FIG. 4 shows diagrammatically a gold-gas refrigerator withthe associated control-device, whilst for clarity only one pair ofcooling units is shown.

FIGS. 5 and 6 show diagrammatically two different views of agold-gasrefrigerator, in which the pump units are arranged parallel to eachother. I

Referring to FIGS. 1, 2 and 3, reference numeral 1 designates a crankcasing, on which the pump units I and II are arranged in a V. Themachine comprises furthermore two pairs of cooling units A A and B Bwhich communicate by ducts with the pump units.

The pump units I and II, comprise each a housing constructed from twoportions 2 and 3. In the portion 2 the partitions 4 and 5 form a closedspace, which is subdivided by the partition 6, the cylinder 7 and themovable piston 8 into two spaces 9 and 10. In the portion 3 a closedspace .is' formed, which is subdivided by the partition 11, the cylinder12 and the piston 13, movable in the former, into the. separated spaces14 and 15. With the portion 3 communicates a further cylindrical portion16, in which the end 77 of the pump rod 17 with the pistons 8 and 13 isadapted to reciprocate; In the cylindrical portion 16 opens out a supply.duct 1%. The. pump rod 17 is connected via a crank driving mechanismhoused in the crank casing 1 with the crank shaft 19, which is coupledin turn with an engine 19'.

The cooling units A A and B B comprise each a cylinder 29, in which theexpansion piston 21 is adapted to reciprocate. Each cooling unitcomprises furthermore a freezer 22, a regcnerator 23, a cooler 24 and acylinder 25, in which the compression piston 26 is adapted to re-'ciprocate; End plates 27, 28 are interconnected by rods 2?. These rods29 are so constructed as to absorb the forces on the cooling units. V

The space 30, on the side of the expansion piston 21 remote from theworking space, is filled with fluid and the space 31 on the side of thecompression piston 25 remote from the working space is also filled withfluid. The space 31 of each of the cooling units A and A communicatesvia duct 32 with the space 14- of the pump unit I, whereas the space 31of .the cooling unit A communicates via a duct 33 with the space 15 ofthe pump unit I. The space 30 of the cooling unit A communicates by wayof a duct 34 with the space 10 of the pump unit II, whereas the space 30of the cooling'unit Ag communicates via a duct 35 with the space 9 ofthe pump unit II. It will appear thcrefromthat, whereasthe ducts 32 and33 are parallel to each other, the ducts 34 and 35.

cross each other. The purpose thereof is to obtain the desired phasedifference between the compression pistons and the expansion pistons ofthe cooling units concerned. V r

The relevant, fluid-filled spaces of the pair of cooling units Bcommunicate in a similar manner with the spaces of the pump units, thearrangement of said cooling units. being, however, such that thefluid-filled spaces 31 are: orientated towards the. pumpunit II, whereasthe fluidfilled spaces 30 are orientated towards the pump unit I. Thespace 31 of the cooling unit B communicates via a duct 36 with the space14 of the pump unit IIandthe,

space 31 of the cooling unit B communicates via a duct 37 with the spaceof the pump unit II. The ducts 36 and 37 are again parallel to eachother. The space 34) of the cooling unit B communicates via a duct 3%with the space 9 of the pump unit I and the space 30 of the cooling unitB communicates via a duct 39 with the space 10 of the pump unit I. Fromthe drawing it will be seen that the ducts 38 and 39 are also parallelto each other.

The cooling units A A B B are furthermore provided with a supply duct 40and an outlet duct 41 for cooling water. It will be apparent that, ifdesired, two or more coolers may be interconnected, so that they aretraversed in series by the coolant.

. The freezers 22 of each cooling unit are all provided with an inlet 43and an outlet 44 for the medium to be cooled. Also the freezers may, ifdesired, be interconnected so that they are traversed in series by themedium to be cooled.

The regenerator 23, the freezer 22 and adjacent parts of each coolingunit are surrounded by insulating material 46. The cooling units arefurthermore provided, for reinforcing the structure, with plates 47,accommodating the cooling units pairwise and being secured to supports48, which are connected with the crank casing l.

The compression pistons 26 and the expansion pistons 21 of all coolingunits are provided with a piston rod 49. Each of these piston rods 49supports a plunger-shaped control-slide 50, which is movable in acylindrical portion 51, which is in open communication at one end withthe connecting duct concerned between the fluid spaces in the coolingunits and the fluid spaces in the pump units. The other side of thecylindrical portion 51 communicates through a duct 52 also freely withthe said connecting duct. With the cylindrical portion 51 communicates afluidoutlet duct 53. The opening of the fluid-outlet duct 53 in theportion 51 is disposed so that it can be released by thecontrol-slide59, when the relevant piston connected with said slide occupies itsdeepest position in the cooling unit. With the cylindrical portion 51communicates furthermore a fluid-inlet duct 54, the opening of which inthe cylindrical portion 51 is disposed so that it is released when thepiston concerned passes beyond its outermost, prescribed position. Withthe cylindrical portion 51 communicate a further fluid-supply duct 55and a further fluid-outlet duct 56, the passages of which are blocked inthe operational condition of the machine.

The operation of the machine will now be described with reference toFIG. 4, in which the hot-gas reciprocating machine of FIGS. 1, 2 and 3is shown diagrammatically. Corresponding structural parts are designatedin FIG. 4 by the same references as in FIGS. 1, 2 and 3. It shouldfurthermore be noted that for the sake of clarity only one pair ofcooling units i.e. A and A is shown in FIG. 4, the various pistons beingshown in their positions occupied when the machine is started.

The control-member not shown in FIGS. 1, 2 and 3 comprises, as is shownin FIG. 4, a control-slide S7, by means of which a number of ports canbe closed or released. The control-slide 57 is connected bya rod 58 witha ring 59, in which an eccentric disc 60, seated on a shaft 61, isadapted to turn. The shaft 61 is provided with a hand wheel 62. Themachine comprises furthermore an oil pump 63, the pump duct of whichopens out in a buffer space 64. The oil suction duct 65 opens out in thereservoir 66. By means of an automatic control-valve 67 the pressure inthe buffer space is kept constant.

The machine operates as follows:

In order to start the machine the hand wheel 62 moves via the eccentricdisc 60 the control-slide 57 into a position in which the port 68 isopen. The control-slide 57 is arranged so that, when the port 68 isopen, also the ports 69 and 70 are free. In this position of the slide57 also the ports 71 and 72 are free. Thus in this position of the slide57 oil can flow out of the buffer space 64 via the duct 73 through theport 71 towards the ports 69 and trate into the cooling units.

through the latter into the oil inlet ducts 55. Thus com pressed oilarrives via the ducts 52 in the spaces 31 and 30 of the cooling units,so that each of the pistons 26 and 21 are urged into their coolingunits. When the controlslide 56 occupies a position in which theopenings 74 of the fluid-outlet ducts 56 are free, the fluid can flowvia the ports and the port 75 into the fluid-outlet duct 7 6.

The duct 76 opens out in the reservoir 66. Thus the pistons 21 and 26are prevented from penetrating further into the cooling units. They thenoccupy their starting positions. At the same time oil can flow out ofthe bulfer space 64 through the duct 73 and the ports 72 and 68 into theduct 18. Consequently, compressed oil is introduced into the space 16 ofthe pump units. Thus the portion 77 of the pump rod 17 is subjected topressure in the direction of the crank shaft, so that the pistons of thepump units are compelled to occupy the positions shown in FIG. 4. If,after the pistons of each pump unit have taken up their aforesaidpositions, a further quantity of oil is supplied to the space 16, thevalve 7 8 is opened during the pressure increase of the oil, so that oilflows out of the space 16 via the duct 79 towards the reservoir 66. Themachine is then ready for starting.

For starting the machine first the hand wheel 62 is actuated so that thecontrol-slide 57 closes the ports 68, 69, 76, 71, 72 and 75. Then themotor driving the crank shaft 19 is caused to rotate. The pump pistons 8and 13 are also set moving so that the fluid columns cause the pistons21 and 26 of the cooling units to move. When the machine starts, theworking spaces of the two cooling units of each pair communicate via aconnecting duct 89, including a variable valve 81, freely with eachother, so that the machine starts without load. Afterwards, inaccordance with the speed of the crank shaft, the control-valve 81 inthe connecting duct is closed, so that the machine starts producing coldaccording to the Sterling cycle.

The fluid leaking out of the system results in that the pistons 21 and26 are urged excessively outwardly by the gas pressure in the workingspace. This is avoided by providing in the portion 51 accommodating thecontrol-slide 5% a port 83, which is released, when the relevant pistonpasses beyond its extreme, prescribed posi tion. The port 83communicates with the fluid supply duct 54, so that fluid can flow'fromthe fluid pump into the, space 31 or 36), when the control-slide 5i)releases the port 83. Thus, the stroke of the piston concerned islimited on the outer side and the fluid leaking away during the strokeis recovered.

if for some reason the pistons 21 or 26 of the cooling units shouldpenetrate too far into the cooling units, the control-slide 56 releasesa port 82, so that fluid can flow via the ducts 53 towards the reservoir66. Thus the pressure in the spaces 30 or 31 cannot rise further, sothat the piston concerned 21 or 26 will not further pene- The extremeinner positions of the pistons 21 and 26 are thus fixed.

The seal between the compression pistons and the expansion pistons andthe surrounding cylinders in the cooling units is formed by rollingdiaphragms $4. In order to keep the desired pressure difference constantwith each of these rolling diaphragms, there are provided controlmembers 85. Each of these control-memhers comprises a cylinder 86, inwhich a plunger 87 is adapted to reciprocate. The space 88 on one sideof the plunger 87 communicates via a duct 89 with the space 90 beneaththe rolling diaphragm 84-. The fluidfilled space 31, on the side of thepiston 26, remote from the working space, communicates via a duct l withcylinder 86. The ducts 89 and 91 include helices 92, which ensure thatrapid pressure variations in the spaces 96 and 31 are damped, so thatthey do not occur in the cylinder 86. With the cylinder 86 communicatesfurthermore a fluid outlet duct 93 and there is provided a helix Thepiston 26 travels with a fair amount of clearance V in its cylinder sothat, since the pressure in the space 31 exceeds the pressure in thespace 90, fluid flows towards the space 90. If no further steps weretaken, the pressures in the spaces 31 and 90 would soon become equal toeach other. However, the fluid fed to the space 99 now flows via theduct 89 to the space 88 in the cylinder 86. The helix 94 is chosensothat with the correct pressure difference the plunger '87 partlyreleases the opening of the duct 93. Thus the fluid fed to the space 88can flow via the duct 93 out of said space.

It is thus achieved that the fluid in the space 90 is constantlyreplaced by freshly supplied fluid. This has the advantage that the gasdiffusing across the rolling diaphragm is removed from the space 90 withthe fluid conducted away.

If for some reason the equilibrium in the pressure difference betweenthe spaces 90 and 31 is disturbed, the following occurs. If the pressurein the working space 97, and hence also in the space 31 increases beyondthe value corresponding to the desired pressure difference,

said pressure will be imparted via the duct 91 and the slot between theplunger 87 and the cylinder 86 to the space 96. Thus the energyequilibrium on the plunger 87 is disturbed. The plunger 87 moves to theleft, so that the duct 93 is closed to a greater extent. Consequently, asmaller quantity of fluid can flow away from the spaces 90 and 88, sothat the pressure in said spaces increases.

When the correct pressure difference is restored, the

plunger 87 re-occupies its initial position and the fluid is againpermitted to flow.

' The fluid leaking away through the fluid outlet duct 93, similarly tothe fluid leaking away from the device in another manner, is replenishedduring each stroke, since the opening 83 of the fluid supply duct 54 isreleased.

FIG. 4 shows for the sake of clarity only one controlmechanism 85;however, in practice, all rolling diaphragms are provided with such acontrol-mechanism.

FIGS. 5 and 6 show diagrammatically a hot-gas reciprocating machine,formed by a cold-gas refrigerator, in two elevations; the pump units Iand II are arranged parallel to each other on a crank casing 101. Thepistons of each of these pump units are connected by means of pistonrods 117, universal joints 118, connecting rods 119 with cranks 121 and120 respectively of the crank shaft 122 accommodated in the crank casing101. The. cranks 120 and 121 are turned through 90 relatively to eachother in order to obtain the desired phase difference between thepistons moving in the cooling units. The machine comprises again twopairs of cooling units A A and B B Said cooling units and the pump unitsI and II maybe constructed in the same manner as the corresponding unitsdescribed with reference to FIGS. 1, 2 and 3.

From the drawing it will be seen that the cooling units A and A arelocated in. a plane located in front of the plane of the pump units Iand II and parallel thereto, whereas the cooling units B and B aredisposed in a plane located behind the plane of the pump units. Thecentre lines of the cooling units A and A cross the centre lines of thecooling units B and B The cooling units A and A communicate on one sideand on the other side via ducts 134 and 135 respectively 8 with the pumpunit II. The ducts 132,"133'and 134, 135 extend pairwise parallel toeach other.

The cooling units B and B communicate on one side via ducts 136 and 137respectively with the pump unit II and on the other side via ducts 138and 139 respectively with the pump unit I, whereas the ducts 136 and 137are substantially parallel to each other and the ducts' 138 and 139 arearranged crosswise. Thus the correct phase difference between thepistons moving in the various'cooling units is obtained. i

The advantage of the machine illustrated in FIGS. 5 and 6 is that thelength thereof, i.e. the distance between the centre lines of the pumpunits'is small as compared with other arrangements of pump units andcooling units. This may be usefulin places where space is a problemiAlthough the drawing shows only two pump units parallel to. each other,it will be obvious that the machine may be extended with further pumpunits without any difliculty.

From the drawing it will also appear that. with the construction of ahot-gas reciprocating machine according to the invention there is, inpractice, a great freedom with respect to the arrangement of the variousunits relative to each other. V 1 i Although four cooling units areshown in the drawing, it will be obvious that it is possible, withoutany difficulty, if the conditions require it, to omit one or more of thecooling units.

What is claimed is:

1. A hot-gas reciprocating apparatus comprising at least two pairs ofunits in each of which a working medium performs a thermodynamic cycle,each unit having a compression space of variable volume and an expansionspace of variable volume, means connecting'said compression space withsaid expansion space, said connect- 1ng means includinga cooler,regenerator and a heat exchanger, said spaces having relativelydiffere'nt mean temperatures, said Working medium adapted to flowalternately in said spaces and through said cooler, regenerator and heatexchanger, a cylinder housing piston-like elements, said piston-likeelements being adapted to move with a relative phase difference in orderto vary the volumes of said compression and expansionspaces, a drivinggear, said piston-like elements being coupled to said driving gear, atleast two pump units, each of said pump units comprising two closed,fluid-filled cylinders, a pair of double-acting pistons being acompression piston and an expansion piston adapted to move in saidfluid-filled cylinders whereas in the first pair of unitseach of thespaces positioned on the side of the associated expansion piston remotefrom said expansion space communicates with one of the spaces on eitherside of one of the pistons of the first pump unit, and each of thespaces positioned on the side of the associated compression pistonremote from said compression space communicates with one of the spaceson either side of one of the pistons of the second pump unit, and inthat of the second pair of units in which the thermo-dynamic cycle isperformed each of the'spaces being positioned on the side of theassociated expansion piston remote from said expansion spacecommunicates with one of the spaces on either side of the other pistonof the second pump unit, and each of the spaces positioned on the sideof the associated compression piston remote from said compression spacecommunicates with one of the spaces on either side of the other pistonof said first pump unit. 1 r

2. A hot-gas reciprocating apparatus as claimed in claim 1,further'comprising a common crank shaft for said pump units and whereinthe pump units are arranged pairwise in the form of a V and areconnected with said common crank shaft, and in that each of the units inwhich the thermo-dynamic cycle is performed is arranged substantiallybetween planes intersecting the center line of the crank shaft and goingthrough the center lines of the pump unitsrso that in a projection to aplane at right 9 angles to the center line of the crank shaft, thecenter lines of the two pump units and the center line of each unit inwhich the thermo-dynarnic cycle is performed form a triangle.

3. A hot-gas reciprocating apparatus as claimed in claim 1, wherein onepair of units in which the thermodynamic cycle is performed is arrangedbetween the two pump units so that the spaces, on the side ofcompression pistons remote from said compression space, are orientatedtowards the first pump unit communicating with said spaces, while thespaces, on the side of the expansion pistons remote from said expansionspace, are orientated towards the second pump unit communicating withsaid spaces and in that the other pair of units in which thethermo-dynamic cycle is performed is arranged between the two pump unitsso that the spaces, on the side of the compression pistons remote fromsaid compression space, are orientated towards the second pump unitcommunicating with said spaces, whereas the spaces, on the side of theexpansion pistons remote from said expansion space, are orientatedtowards the first pump unit communicating with said spaces.

4. A hot-gas reciprocating apparatus comprising at least two pairs ofunits in which a working medium performs a thermo-dynamic cycle, eachunit having a compression space of variable v'olume and an expansionspace of variable volume, means connecting said compression space withsaid expansion space, said connecting means including a cooler,regenerator and a heat exchanger, said spaces having relativelydifferent mean temperatures, said working medium adapted to flowalternately in said spaces and through said cooler, regenerator and heatexchanger, a cylinder housing piston-like elements, said piston-likeelements being adapted to move with a relative phase difference in orderto vary the volumes of said compression and expansion spaces, a drivinggear, said piston-like elements being coupled to said driving gear, atleast two pump units arranged parallel to each other, each of said pumpunits comprising two closed, fluidfilled cylinders, a pair ofdouble-acting pistons being a compression piston and an expansion pistonadapted to move in said fluid-filled cylinders whereas in the first pairof units each of the spaces positioned on the side of the associatedexpansion piston remote from said expansion space communicates with oneof the spaces on either side of one of the pistons of the first pumpunit, and each of the spaces positioned on the side of the associatedcompression piston remote from said compression space communicates withone of the spaces on either side of one of the pistons of the secondpump unit, and in that of the second pair of units in which thether-rno-dynamic cycle is per-formed each of the spaces being positionedon the side of the associated expansion piston remote from saidexpansion space communicates with one of the spaces on either side ofthe other piston of the second pump unit, and each of the spacesp'ositioned on the side of the associated compression pistion remotefrom said compression space communicates with one of the spaces oneither side of the other piston of said first pump unit, one of the pairof units in which the thermo-dynamic cycle is performed communicatingwith said pump units @being arranged in a plane extending parallel toand in front of the plane of said pump units and the other pair of unitsin which said thermodynamic cycle is performed communicating with saidpump :units and being arranged in a plane extending parallel to andbehind the plane of said pump units, and said units in which saidtherrno-dynamic cycle is performed being arranged in their respectiveplanes so that in a projection through the plane of said pump units thecenter lines of one pair of said units in which said thermo-dynarniccycle is performed intersect the center lines of said relevant units ofthe other pair.

5. A hot-gas reciprocating apparatus comprising at least two pairs ofunits in which a working medium performs a thermodynamic cycle, eachuni-t having a compression space of variable volume and an expansionspace of variable volume, means connecting said compression space withsaid expansion space, said connecting means including a cooler,regenerator and a heat exchanger, said spaces having relativelydifferent mean temperatures, said working medium adapted to flowalternately in said spaces and through said cooler, regenerator and heatexchanger, a cylinder housing piston-like elements, said piston-likeelements being adapted to move with a relative phase difference in orderto vary the volumes of said compression and expansion spaces, a drivinggear, said pistonlike elements being coupled to said driving gear, atleast two pump units arranged parallel to each other, each of said pumpunits comprising two closed, fluid-filled cylinders, a pair ofdouble-acting pistons being a compression piston and an expansion pistonadapted to move in said fluid-filled cylinders whereas in the first pairof units each of the spaces positioned on the side of the associatedexpansion piston remote from said expansion space communicates with oneof the spaces on either side of one of the pistons of the first pumpunit, and each of the spaces positioned on the side of the associatedcompression piston remote from said compression space communicates Withone of the spaces on either side of one of the pistons of the secondpump unit, and in that of the second pair of units in which thethermo-dynamic cycle is performed each of the spaces being positioned onthe side of the associated expansion piston remote from said expansionspace communicates with one of the spaces on either side of the otherpiston of the second pump unit, and each of the spaces positioned on theside of the associated compression piston remote from said compressionspace communicates with one of the spaces on either side of the otherpiston of said first pump unit, plural control slides, each piston ineach unit in which said thermo-dynamic cycle is performed beingconnected to one of said control slides, the latter being displaced uponmovement of an associated piston along a portion of said fluid-filledspace on the side of said piston remote from said expansion space, andat least one fluid inlet and at least one fluid outlet in said portionof said fluid-filled space, said inlet and outlet openings being soarranged that said inlet is opened when the piston passes to itsoutermost predetermined position and the outlet is opened when thepiston occupies its inner-most predetermined position in said unit inwhich a thermodynamic cycle is performed.

6. A hot-gas reciprocating apparatus as claimed in claim 5, wherein eachof the pistons adapted to reciprocate in the cylinder of each unit inwhich the thermodynamic cycle is performed further comprises anothercylindrical part constituting said control-slide which is adapted tomove in a further cylindrical part of each of the cylinders is in whichsaid piston-like elements are moveable and in that the apparatuscomprises at least one duct interconnecting the two spaces on eitherside of the control-slide and in that the inlet duct and the outlet ductare in contact with the wall of said other cylindrical part.

7. A hot-gas reciprocating apparatus as claimed in claim 5 furthercomprising a fluid supply duct and wherein each of the fluid-filledspaces in each unit in which the thermo-dynamic cycle is performedcommunicates with said fluid supply duct, the passage of which isblocked in operation of the apparatus, whereas at the location of thecontrol-slide a further fluid outlet duct opens out, the passage ofwhich is also blocked in the operation of the apparatus and in that thepassages of said ducts can be released when the apparatus is preparedfor starting and in that the openings of the outlet ducts are arrangedso that they are uncovered when the relevant piston occupies itsstarting position.-

8. A hot-gas reciprocating apparatus as claimed in claim 7 furthercomprising a closed cylinder, a further piston-like body adapted to movetherein, and wherein 1 1 the interconnected pistons of each of the pumpunits are furthermore connected With said piston-like body locatedsubstantially in their center lines, and in that the space above saidpiston-like body communicates With said fluid supply duct through whichcompressed fluid can be introduced into said space whereby the pistonsof the pump units are driven in their starting positions.

'9. A hot-gas reciprocating apparatus as claimed in claim l-fu-rthercomprising a control member, a plurality of fluid supply ducts andoutlet ducts, a pump device having a pump ductpwhich can be caused tocommunicate through said control memlver with said fluid supply ducts ofthe apparatus, and in that there is furthermore pr0- vided a fluidreservoir, with which the fluid outlet ducts of said apparatus can becaused to communicate through said control member.

. 12 1 References Cited by the Examiner UNITED STATES PATENTS 2,484,892'10/ 49 Van Heeekeren 62-6 X 2,567,637 9/51 De Brey et a1. 60-24,2,590,519 3/52 Du Pr 60-24 2,616,245 11/52 Van Weenen 60-24 2,616,24811/52 De Brey'et al. 2 60-24 2,657,528 11/53 Jonkers et a1. 60-242,657,552 11/53 Jonkers et a1. 60-24 X 2,664,699 1/54 Kohler v60-242,771,751 11/56 Jonkers et a1. 62-6 X 3,117,414 1/64 Daniels et a1.60-24 JULIUS E. WEST, Prinintry Examiner. EDGAR W..GEOGHEGAN, Examiner.

1. A HOT-GAS RECIPROCATING APPARATUS COMPRISING AT LEAST TWO PAIRS OF UNITS IN EACH OF WHICH IS WORKING MEDIUM PERFORMS A THERMODYNAMIC CYCLE, EACH UNIT HAVING A COMPRESSION SPACE OF VARIABLE VOLUME AND AN EXPANSION SPACE OF VARIABLE VOLUME, MEANS CONNECTING SAID COMPRESSION SPACE WITH SAID EXPANSION SPACE, SAID CONNECTING MEANS INCLUDING A COOLER, REGENERATOR AND A HEAT EXCHANGER, SAID SPACES HAVING RELATIVELY DIFFERENT MEAN TEMPERATURES, SAID WORKING MEDIUM ADAPTED TO FLOW ALTERNATELY IN SAID SPACES AND THROUGH SAID COOLER, REGENERATOR AND HEAT EXCHANGER, A CYLINDER HOUSING PISTON-LIKE ELEMENTS, SAID PISTON-LIKE ELEMENTS BEING ADAPTED TO MOVE WITH A RELATIVE PHASE DIFFERENCE IN ORDER TO VARY THE VOLUMES OF SAID COMPRESSION AND EXPANSION SPACES, A DRIVING GEAR, SAID PISTON-LIKE ELEMENTS BEING COUPLED TO SAID DRIVING GEAR, AT LEAST TWO PUMP UNITS, EACH OF SAID PUMP UNITS COMPRISING TWO CLOSED, FLUID-FILLED CYLINDERS, A PAIR OF DOBULE-ACTING PISTON BEING A COMPRESSION PISTON AND AN EXPANSION PISTON ADAPTED TO MOVE IN SAID FLUID-FILLED CYLINDERS WHEREAS IN THE FIRST PAIR OF UNITS EACH OF THE SPACES POSITIONED ON THE SIDE OF THE ASSOCIATED EXPANSION PISTON REMOTE FROM SAID EXPANSION SPACE COMMUNICATES WITH ONE OF THE SPACES ON EITHER SIDE OF ONE OF 